//
//  UIImage+UIImageScale.m
//  CorpKnowlGroup
//
//  Created by Ann Yao on 12-7-23.
//  Copyright (c) 2012年 __MyCompanyName__. All rights reserved.
//

#import "UIImage+UIImageScale.h"

@implementation UIImage (UIImageScale)

//截取部分图像,如果图像是@2x,则是实际尺寸的大小截取（一般乘以2）
-(UIImage*)getSubImage:(CGRect)rect  
{  
    CGImageRef subImageRef = CGImageCreateWithImageInRect(self.CGImage, rect);  
    CGRect smallBounds = CGRectMake(0, 0, CGImageGetWidth(subImageRef), CGImageGetHeight(subImageRef));  
    
    UIGraphicsBeginImageContext(smallBounds.size);  
    CGContextRef context = UIGraphicsGetCurrentContext();  
    CGContextDrawImage(context, smallBounds, subImageRef);  
    UIImage* smallImage = [UIImage imageWithCGImage:subImageRef];  
    UIGraphicsEndImageContext();  
    CFRelease(subImageRef);
    return smallImage;  
}  

//等比例缩放  
-(UIImage*)scaleToSize:(CGSize)size   
{  
    CGFloat width = CGImageGetWidth(self.CGImage);  
    CGFloat height = CGImageGetHeight(self.CGImage);  
    
    float verticalRadio = size.height*1.0/height;   
    float horizontalRadio = size.width*1.0/width;  
    
    float radio = 1;  
    if(verticalRadio>1 && horizontalRadio>1)  
    {  
        radio = verticalRadio > horizontalRadio ? horizontalRadio : verticalRadio;     
    }  
    else  
    {  
        radio = verticalRadio < horizontalRadio ? verticalRadio : horizontalRadio;     
    }  
    
    width = width*radio;  
    height = height*radio;  
    
    int xPos = (size.width - width)/2;  
    int yPos = (size.height-height)/2;  
    
    // 创建一个bitmap的context    
    // 并把它设置成为当前正在使用的context    
    UIGraphicsBeginImageContext(size);    
    
    // 绘制改变大小的图片    
    [self drawInRect:CGRectMake(xPos, yPos, width, height)];    
    
    // 从当前context中创建一个改变大小后的图片    
    UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext();    
    
    // 使当前的context出堆栈    
    UIGraphicsEndImageContext();    
    
    // 返回新的改变大小后的图片    
    return scaledImage;  
}

- (UIImage *)getSquareImage
{
    CGSize size = self.size;
    CGRect rect;
    if (size.width>size.height)
    {
        rect = CGRectMake((size.width-size.height)/2, 0, size.height, size.height);
    }
    else
    {
        rect = CGRectMake(0, (size.height-size.width)/2, size.width, size.width);
    }
    
    UIImage *newImage = [self getSubImage:rect];
    return newImage;
}


@end
